Automatic safety switch locking mechanism



March 27, 1951 E. J. KROMHOLZ AUTOMATIC SAFETY SWITCH LOCKING MECHANISM 2 Sheets-Sheet 1 Filed Aug. 20, 1948 WWQ March 27, 1951 E. 1. KROMHOLZ 2,546,454

AUTOMATIC SAFETY SWITCH LOCKING MECHANISM Filed Aug. 20, 1948 2 Sheets-Sheet 2 Patented Mar. 27, 1951 OFFICE AUTOMATIC SAFETY SWITCH LOCKING MECHANISM Edward I. Kromholz, Rockford, Ill.

Application August 20, 1948, Serial N0. 45,227

Claims This invention relates to a new and improved automatic safety switch locking mechanism for spring or hand-thrown switches on railroads.

The conventional spring switch has long been known to be subject to two serious objections,

namely, first, that the points are caused to move back and forth repeatedly when an engine pulls a few cars out of a siding, the points being thrown back and forth as many times as there are passing carriages, all of which means a lot of aimless c1at ter and needless wear and tear on all the equipment involved, and, second, that the points worn by such abuse are apt to break and, if that is not found out promptly, cause a serious Wreck by reason of the open switch condition, or the badly worn points, if still otherwise intact, may not close tightly enough and thus give rise to the possibility of causing a wreck due to the partially open switch being accidentally opened farther. It is, therefore, the principal object of my invention to provide a magnetically operated locking mechanism which is connected in circuit with the block signal circuit so as to be energized to insure freezing the switch points safely in closed position when an engine or train approaches on the main track, but which is also arranged to be energized to freeze the switch points in open position when the switch is thrown by hand or when an engine or train runs out of the siding" onto the main track, whereby in the latter case to avoid having the points thrown back and forth with the clatter and wear and tear mentioned before, the switch being released to close only when the switched engine or train has run, say. thirty" feet on the main track away from the switch, thereby avoiding the possibility of the condition arising that frequently causes a lot of damage to railway equipment, namely, where the switch points close under spring pressure when part of a train or one end of a car thereof is still in the siding, and the engineer, not aware of that, stops the forward travel of the engine too soon and starts backing up. The locking mechanism comprises dogs engageable in either of two sets of notches provided in a keeper bar reciprocable with the switch throw-bar to lock the switch points, positively in either open or closed position, the. dogs being pivotally mounted on a stationary support relative to which the keeper-bar is guided for sliding movement, and there being a yoke for actuating the dogs reciprocable relative to the dogs, spring-pressed to a retracted position and operable magnetically in the other direction.

. The energization of. the controlling magnet i taken care of automatically by tie-in with the 2 block signal circuit and is maintained so long as the train for whose safe travel relative to the switch points the locking dogs have been actuated, thereby positively" eliminating any danger of accidents due to faulty operation of the switch.

The invention is illustrated in the accompanying drawings, in which Fig. l is a plan view of a typical spring switch" installation equipped with my improved magnetically operated locking mechanism? Fig. 2 is a front elevation of Fig. 1;

Fig. 3 is a plan view of the locking mechanism on a larger scale;

r Fig 4 is a front view of Fig. 3 taken on section line 4-4 thereof; I

Fig. 5 is an eleetr'iem circuit diagram applicable to Figs. 1 to 4;

.Fig. 6 is a plan View similar to a portion of- Fig'. 3, but showing a modified or alternative construct'i'on, and i Fig. 7 is another plan view similar to Fig. 6 showing still another modified or alternative coris'truction.

Similar reference numerals are applied to corresponding parts" throughout these views.

Referring" to Figs. 1 and 2, the reference nfi-' merals 8 and 9 designate the conventional points rqr the springfswitcli mustrated, which are move able to the right with reference to the main track" rails ID and H against resistance of a Spring; S"

in the cylinder [2, as, for example, when a 10ccmotive comes out of a siding onto the main track; The cylinder 12 is] connected to one end of the usual throw-bar [3 which inturn' is pivotally connected with the points- 8 and 9' sothat these points move together from one extreme position to the other; cylinder l2 in cooperation with the aforesaid spring have a piston rod 14 extending therefrom from the cylinder to the arm l5 attached to the lower end of the vertical shaft IB' in the switch stand [1, carrying the usual signal target I8 on its upper end, and arranged to be turned in the usual way'by nieans of a lever l 9 when thev latter is swungup'wardl'y from its lower locked position to the usual horizontal operating position. With this conventional arrangement it is clear that thepoints' 8' and Swill be moved back'and' forth withthe throw-bar ['3 as many times as there are passing carriageswhenever' a locomotive with of withoutsome. cars attached comes out of the siding onto the main track,tlius accounting for all of the clatter and needless wear and tear on all of the. equipment" involved, and it is easy to understand that such operation results in excessive wear on The usual piston parts P working in the the relatively slender points and that they are, therefore, apt to break and cause a serious wreck, or the wear on the points may be responsible for the switch not being closed tightly enough, thus giving rise to the possibility of a wreck due to the switch being accidentally opened farther.

In accordance with my invention the two ties 20, onto one end of which the base 2| of the switch stand is bolted and which extend under the rails I and l l and have these rails fastened thereto, as indicated, are extended on the other side of the track, as indicated at 22, to support the magnetic locking mechanism 23 of my invention illustrated most clearly in Figs. 3 and 4. The throw-bar [3, in accordance with my invention, is laterally adjustably connected by means of a bolt 24 with the end of a keeper bar 25 forming, in effect, a direct extension of the throw-bar. This keeper bar has two sets of keepers in the form of V-notches 26 and 21 provided therein to cooperate wedgingly with the V-shaped teeth 28 on the free ends of dogs 29 disposed on opposite sides of the bar 25 and pivotally mounted at their remote ends, as at 30, on a cross-piece 3|. The cross-piece 31 is preferably a metal strap bolted at its ends, as at 32, to the top of the ties '20 and having its intermediate portion 33 bent downwardly into offset relation to'the attached ends to form a depressed support for the pivoted ends of the dogs 29. The dogs 29 are shown in released or retracted position in Fig. 3,but it will be understood that they engage in notches 26 when holding the switch points 8 and 9 in open position, and that they engage in notches 21 when holding these points in closed position. A yoke 34 is reciprocable with the armature 35 of the electro-magnetic coil 36 to actuate the dogs 29 instantly whenever this electro-magnetic coil is energized. This yoke 34 is slidably supported on the pivoted ends of the dogs 29 and carries a pair of rollers 31 mounted on rivets 38 for anti-friction rolling contact on the backs of the do s 29,,so as to move the dogs inwardlyfor tight locking engagement in the notches 26,or 21, as the case may be, when the yoke 34 has been moved forward enough to run the rollers 31 to the toothed free ends of the dogs. The V shape of the teeth 28 gives a wedging action to insure complete opening movement and complete closing movement of the switch points, because if the notches are not in good register with the teeth on the dogs, the dogs will force the switch points to move the necessary amount when the dogs are pressed home. Assuming now that the energization of the controlling electromagnetic coil 36 is maintained so long as the train for whose safe travel relative to the switch points the locking dogs have been actuated, it should be clear that the danger of any accidents due to farther opening of the switch. is positively eliminated, also that when the switch points 8 and 9 are moved to the right by the pilot wheels of the locomotive coming out of the siding the circuit for the electro-magnetic coil 36 is closed and kept closed thereafter until the locomotive and the car or cars thereto attached have all beenrun onto the main track to a distance of say thirty feet from the switch, thereby eliminating not only the clatter and wear incident to numerous back and forth movements of the switch points, but also the hazards which such wear is responsibe for, there being also avoided the possibility .of the condition arising that has frequently caused a lot of damage to railway equipment, namely, where the switch 4 points close under spring pressure when part of a train or one end of a car thereof is still on the siding unbeknownst to the engineer when he stops the forward travel of the engine too soon and starts backing up. The yoke 34 in moving to its locking position moving over the pivoted ends of the dogs toward the toothed portions and, therefore, holds the dogs positively in locked position. The yoke 34 has an upwardly bent rear flange 39 that is adjustably connected by bolts 40 with ears 4| on the ends of a cross-piece 42 provided on the end of the armature 35, whereby to transmit movement from the armature 35 to the yoke 34 and permit accurately predetermining the forward limit position of the yoke 34 with respect to the dogs 29 by proper adjustment of the bolts 40 in reference to the throw of the armature 35. A- rod 43 (Figs. 1 and 2) extends rearwardly from the armature 35 through a hole in the cross portion of a U-shaped yoke 44 that is rigidly connected to the frame of the electromagnet and a wing nut 45 is threaded adjustably on the outer end of the rod 43 to compress a coiled compression spring 46 to the desired extent, this spring being coiled around the rod 43 between the cross-portion of the yoke 44 and the nut 45. In that way the armature 35 is assured of immediate return to retracted position the instant the electro-magnetic coil 36 is deenergized, and the yoke 34 is accordingly returned to retracted position, releasing the dogs 29. The mechanism 23 is carried on straps 41 bolted, as at 48, to the ties 20, the intermediate portions 49 of these straps being depressed similarly as the intermediate portion 33 of the strap 31, for a similar reason. A switch point circuit control switch 59 has its crank 5| pivotally connected by a link 52 with the adjacent switch point 8, as

shown in Fig. 1 to close the circuit through coil 36 automatically whenever the points 8 and 9 are shifted to open position, whether by hand or by a locomotive or train coming out of the siding.

The operation of the locking mechanism is diagrammatically illustrated in Fig. 5 in which 53 and 54 are the track relays, 55 the time release relay, and 50 the switch point circuit control switch. The conventional track batteries are in dicated at El and B2 and the usual insulated joints are indicated at 56 for the main tracks I0 and II, and at 51 are indicated similar joints for the tracks 58 in the siding. 59 designates the key release between the line 69 and the coil 36 of the magnetic locking mechanism 23. Assuming the key release 59 is in the closed circuit position shown and that a locomotive, with or without cars attached, one of whose trucks is indicated at T, has run from the siding onto the main track, the

battery B2 is short circuited and track relay 53* is closed as shown and the electro-magnetic coil 36 is accordingly energized, freezing the switch points 8 and 9 in the open position and they remain so until the locomotive and the car or cars attached have passed the joints 56 located a distance of say thirty feet from the switch 89. A- switchman, after unlocking lever l 9, may also i open the switch by means of lever I9 and thereby cause relay 53 to close and freeze the points 8--9- After the train has passed joints 56, going away from the switch, relay 53- in open position.

opens and relay 54 closes but only after the time release 55 has permitted the electro-magnetic coil 36 to deenergize long enough to release the dogs Hence, regard-' 29 and let the switch 89 close. less of what the engineer-may do, he cannot run afoul of the switch, because'if he starts-backing gar-arse up before his train has passed the joints 56 the switch is certain to be locked open and no damage to any railway equipment could therefore result, and, on the other hand, if he starts backing up after his train has passed the joints 56 the switch is certain to be closed. There is no possibility of having the switch closed with part of the train on the main track and the rest on thesiding or one end of a car on the main track and the other end on the other track. It is also clear that a train approaching the switch 8 9 on the main track running against the points will by its weight and the shunting of the tracks, in the manner common to block signal operation, cause relay 54 to close and thereby freeze the points 39 in closed position. I

disclosed in Fig. 6, the locking dogs may be of the form shown at 29a with the locking teeth 2811 near the pivoted ends of the dogs instead of at the free ends. With that arrangement it is obvious that when the rollers 3'! run outwardly to the free ends of the dogs a mechanical advantage" is obtained insuring tighter gripping of the keeper bar 25. The operation with this construc tidri is otherwise the same" as with the other.

With the construction disclosed in Fig. 7, in which the dogs 296 are in the form of bell-crank levers pivoted, as at 382), intermediate their ends and operable by means of links 5| that are pivoted, as at 62, to the yoke 34b and have pin and slot connections, as at 63, with the dogs 2%, a still greater mechanical advantage is obtainable insofar as tightly gripping the keeper bar 25b is concerned, and the dogs are moreover positively retracted with respect to the bar when the electro-magnetic coil 36 is deenergiz'ed. The notches 28b and 21b are rounded as shown to match the rounded ends 286 on the dogs 29b and to allow also for the oscillatory movement of the dogs to and from locking position. The operation with this construction is otherwise the same as with the others.

It is believed that the foregoing description conveys a good understanding of the objects and advantages of my invention. The appended claims have been drawn to cover all legitimate modifications and adaptations.

I claim:

1. In an automatic switch lock for railroads, comprising a throw-bar connected with the switch members to be locked, and spring pressed switch operating mechanism connected with one end thereof and functioning normally to close said switch members, the improvement which consists in the provision of automatically operable switch locking mechanism for selectively locking said switch members in either closed or open position comprising a keeper bar which is a direct extension of the throw-bar and has V- notches provided in opposite sides thereof, a pair of opposed elongated V-toothed latch members each pivoted at one end on a stationary support for releasably locking said keeper-bar, the latter being reciprocable relative to said support between said latch members, a yoke adapted to confine the latch members in looking position movable relative to said latch members to engage the same with a cam action from their pivoted ends toward their free ends to force the same inwardly toward each other with mechanical advantage into locked position with their V-teeth firmly wedgingly engaged in the notches, spring means for retracting said yoke, the V-teeth being freely disengageable from the notches to permit freedoni of movement of the throw-bar when the.

over the switch, whereby the keeper-bar is held in locked position during the passage of atrain of cars over said switch.

2. In a railway switch lock, the combination of a stationary support, a pair of locking dogs pivoted thereon in spaced relation to swing toward one another to locking position, a keeper bar connected to be movable with the throw-bar or a railway switch and reciprocable between said dogs, said keeper bar having V-notches provided in opposite sides thereof in longitudinally spaced relation positioned for engagement by V-teeth on said dogs in locked position when the switch is open and in closed position, respectively, the v-te'eth having wedging engagement in the V- notches when the dogs are in locked position but permitting free movement of the keeper-bar relative to the teeth when the dogs are released, and an operator for said dogs reciprocable relative thereto so as to force the dogs toward locked relation positioned for engagement by V-teeth on said dogs in locked position when the switch is in open and in closed position, respectively, the V teeth having wedging engagement in the V- notches when the dogs are in locked position but permitting free movement of the keeper-bar relative to the teeth when the dogs are releasd, a yoke reciprocable relative to said dogs carrying rollers to ride on the dogs for anti-friction camming of the dogs to locked position upon movement of the yoke in one direction and for release thereof upon movement of the yoke in the other direction, and means for operating said yoke.

4. In a railway switch lock, the combination of a stationary support, a pair of locking dogs pivoted therein in spaced relation to swing toward one another to locking position, a keeper bar connected to be movable with the throw-bar of a railway switch and reciprocable between said dogs, said keeper bar having notches provided in opposite sides thereof in longitudinally spaced relation to receive portions of said dogs in locked position, said dogs being of bell-crank form pivotally mounted intermediate their ends on said support, toggle links pivotally and slidably connected to the outer ends of said dogs, and an op-' erator for said dogs pivotally connected to the other ends of said links and reciprocable relative to said dogs to force the dogs into locking engagement with the keeper-bar with a toggle action.

5. In a railway switch lock, the combination of a stationary support, a pair of locking dogs pivoted thereon in spaced relation to swing toward one another to locking position, a keeper bar connected to be movable with the throw-bar of a railway switch and reciprocable between said dogs, said keeper bar having notches provided in opposite sides thereof in longitudinally spaced relation positioned for engagement by said dogs in locked position when'the switch is in open and in closed position, respectively, the dogs having projections on their inner sides intermediate their ends for locking engagement in said notches, a yoke having operative camming engagement with the outer sides of said dogs, and means for reciprocating said yoke to shift said dogs to looking position upon movement of the yoke in one direction and to release the same upon movement in the other direction.

6. A switch lock as set forth in claim 1, wherein the V-teeth on the latch members are provided intermediate the ends of said members, and the yoke in moving to locked position moves past the toothed portion toward the free ends thereof, whereby increased mechanical advantage is obtained in the forcing of the teeth into firm engagement in the notches.

'7. A switch look as set forth in claim 1, wherein the longitudinal edges of the latch members on the opposite side from the toothed portions provide cam surfaces for cooperation with the yoke, and said yoke carrying rollers arranged to ride on said surfaces for anti-friction camming of the latch members to locked position.

8. A switch lock as set forth in claim 1, wherein the V-teeth on the latch members are provided intermediate the ends of said members, and the yoke in moving to locked position moves past the toothed portion toward the free ends thereof, whereby increased mechanical advantage is obtained in the forcing of the teeth into firm eng agement in the notches, the longitudinal edges of the latch members on the opposite side from the toothed portions providing cam surfaces for cooperation with the yoke, and said yoke carrying rollers arranged to ride on said surfaces for anti-friction camming of the latch members to locked position.

9. In a switch locking apparatus, in combination, a switch member having spring means normally tending to close the same, a lock therefor adapted to lock it selectively in either extreme position opened or closed, a switch lock circuit, and two track circuits each including the usual track batteries and comprising means for closing said switch lock circuit, the one track circuit being short-circuited by a train passing the switch from the associated siding or on the main track, whereby the switch member is locked in open position in the first instance and in closed position in the second instance.

10. In a switch locking apparatus, in combination, a switch member having spring means normally tending to close the same, a lock therefor adapted to lock it selectively in either extreme position opened or closed, a switch lock circuit, and two track circuits each including the usual track batteries and comprising means for closing said switch lock circuit, the one track circuit being short-circuited by a train passing the switch from the associated siding or on the main track, whereby the switch member is locked in open position in the first instance and in closed position in the second instance, the other track circuit including a time release.

EDWARD J. KROMHOLZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,703,254 Stuart Feb. 26, 1929 1,825,469 Milton Sept. 29, 1931 1,980,084 Peabody Nov. 6, 1934 2,093,170 McCann Sept. 14, 1937 

